Abstract:

Accelerated release of carbon from soils is one
of the most important feedbacks related to anthropogenically
induced climate change. Studies addressing the mechanisms
for soil carbon release through organic matter decomposition
have focused on the effect of changes in the average temperature,
with little attention to changes in temperature variability.
Anthropogenic activities are likely to modify both
the average state and the variability of the climatic system;
therefore, the effects of future warming on decomposition
should not only focus on trends in the average temperature,
but also variability expressed as a change of the probability
distribution of temperature. Using analytical and numerical
analyses we tested common relationships between temperature
and respiration and found that the variability of temperature
plays an important role determining respiration rates
of soil organic matter. Changes in temperature variability,
without changes in the average temperature, can affect the
amount of carbon released through respiration over the longterm.
Furthermore, simultaneous changes in the average and
variance of temperature can either amplify or dampen the release
of carbon through soil respiration as climate regimes
change. These effects depend on the degree of convexity of
the relationship between temperature and respiration and the
magnitude of the change in temperature variance. A potential
consequence of this effect of variability would be higher
respiration in regions where both the mean and variance of
temperature are expected to increase, such as in some low
latitude regions; and lower amounts of respiration where the
average temperature is expected to increase and the variance
to decrease, such as in northern high latitudes.

Description:

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